Modern industrial machines are often operated with the help of touch screens, or so-called touch displays, which feature, for example, an arrangement of touch-sensitive front-panel areas. The touch-sensitive front-panel areas could be constructed and provided, for example, as short-travel keys or click buttons for initiating, when contacted, a triggering of a process assigned to the touch-sensitive front-panel area. However, a disadvantage in such touch displays is that, particularly under poor lighting conditions, the likelihood of incorrect activation increases.